JPS58106396A - Production of heat-exchanging medium - Google Patents

Abstract

PURPOSE:To enable to form a heat-exchanging medium without damaging an oxide film, by a method wherein an oxide film having a specified thickness is produced on the surface of an aluminum blank material, and the material is subjected to drawless press working. CONSTITUTION:After producing an oxide film on the surface of an aluminum or an aluminum alloy material, the blank material is subjected to drawless press working to produce the heat-exchanging medium. The oxide film produced prior to the drawless press working step has a film thickness of about 2-10mg/dm<2>, preferably about 5-8mg/dm<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a heat exchange medium, and when producing a heat exchange medium by applying drawless press processing to aluminum or an aluminum alloy, the present invention relates to a method for producing a heat exchange medium. By forming a surface oxide film, the production efficiency of producing heat exchange media from aluminum or aluminum alloy materials is further improved, and production costs are reduced. Film thickness: approximately 2 to 1O/dm2, preferably approximately 5 to 8
rng/dlT12, even if a surface oxide film is formed before the drawless press process, the oxide film will not be damaged during the drawless press process, the forming process is easy, the manufacturing yield is extremely high, and the It is an object of the present invention to provide a method for manufacturing a heat exchange medium that is inexpensive, has excellent heat exchange efficiency, and is highly corrosion resistant.

Conventionally, heat exchange media made of aluminum or aluminum alloy (hereinafter simply referred to as aluminum) have been produced by forming an aluminum material into a predetermined shape as a heat exchange medium by drawless pressing, and then treating the surface of the aluminum material to transfer heat. Manufactured to be corrosion resistant as an exchange medium. However, this manufacturing method, which involves surface treatment after drawless press processing, cannot completely remove the oil that adheres during drawless press processing, resulting in uneven surface treatment, poor corrosion resistance and heat exchange efficiency, and furthermore, It has the drawbacks of poor manufacturing efficiency and high cost.

Therefore, in order to improve manufacturing efficiency, etc., a method of manufacturing heat exchange media by performing drawless press processing after surface treatment is considered. However, if drawless press processing is performed simply after surface treatment, drawless press processing Sometimes the surface treatment film is damaged, resulting in poor corrosion resistance and heat exchange efficiency as a heat exchange medium, and it is not enough to simply perform the surface treatment process before the drawless press process.

For example, after forming a coating layer on the surface of an aluminum material,
If the fin material is manufactured from this material by drawless pressing, cracks may occur at the corner of the ladder during the drawless pressing process, or part of the flare may be damaged, so the heat exchange performance of the fin material after processing may be affected. or the corrosion resistance may deteriorate significantly.

In addition, when a fin material is manufactured by drawless pressing after forming a boehmite film on the surface of an aluminum material, there is a drawback that, for example, cracks occur at the ironed part during drawless pressing, as in the case described above. .

The inventor of the present invention discovered that when attempting to create a heat exchange medium by performing drawless press processing after forming a film on the aluminum surface,
When we investigated in detail why the heat exchange medium was a defective product, we discovered that the thickness of the film on the aluminum surface is closely related to the drawless press processing, and we decided to increase the thickness of the surface treatment film by approximately 2. ~lO■/'dm2, preferably about 5 to 8■/dm2, even if a heat exchange medium is created by drawless pressing after film formation, defects will not occur in the surface treatment film, improving corrosion resistance and heat exchange. It becomes a heat exchange medium with good efficiency, and since the surface of the aluminum material can be treated before drawless press processing, the manufacturing efficiency of the heat exchange medium is improved and manufacturing costs are reduced.

Examples of the method for producing a heat exchange medium according to the present invention will be described below.

Example 1 Thin wrought material made of JIS1200-H26 aluminum alloy (width soo m, length: (oooa, thickness 01
10 hours) and sodium hypochlorite aqueous solution (C20 concentration 200 ppm).

After forming an oxide film on the surface of the wrought material by immersing it in pllo, 6-108) at a temperature of about 80-85°C for about 3 minutes, it was washed with water, and then washed at a temperature of about 0.5%, pH 11.2. treated with a water glass solution for about 30 seconds at about λO ℃,
After that, it is washed with water after a shower, and then dried at 100° C. for 30 seconds. The thickness of the hydrophilic film thus formed on the surface of the wrought material is approximately 5 cm/ckr? Met.

Next, in order to configure the expanded material on which the hydrophilic film has been formed as described above as a fin material, drawless press processing is performed to form a fin material.

Example 2 The same aluminum alloy wrought material as in Example 1 was prepared with piI6
After being immersed in demineralized water B at a temperature of about 95° C. for about 5 minutes to form an oxide film with a thickness of about 65 cm/drr+2 on the surface of the wrought material, it is then dried.

Next, the wrought material on which the oxide film has been formed as described above is subjected to drawless pressing to form a desired fin material.

Example 3 The same aluminum alloy wrought material as in Example 1 was heated to pH 10.
, 6-10J3 sodium hypochlorite aqueous solution (C20
The wrought material is dipped in 200 ppm (concentration 200 ppm) at a temperature of about 80 to 85 DEG C. for about 5 minutes to form an oxide film with a thickness of about 8 .mu.m/dm12 on the surface of the wrought material, followed by washing with water and drying.

Next, the wrought material on which the oxide film has been formed as described above is subjected to drawless press processing to form a fin material having a desired shape.

Comparative Example A wrought aluminum alloy material similar to the above example was prepared using 1) H
About 3% of
After immersion treatment for 5 minutes to form an oxide film on the surface of the wrought material,
It is immersed in a water glass solution having a concentration of 1% and a pH of 11.2 at a temperature of about 95° C. for about 45 seconds, followed by a shower, immersion washing, and drying. The thickness of the film formed on the surface of the rolled and stretched material is approximately 12.5 mg.
/arrr'.

Next, the wrought material on which the surface film has been formed as described above is subjected to drawless pressing to form a fin material.

In the above Examples and Comparative Examples, when examining the fin materials made by drawless press processing, it was found that the fin materials of Examples 1 to 3 did not cause any abnormality during drawless processing, but cracks occurred at the ironed portions due to drawless press processing, for example. There was no occurrence of damage or damage to part of the flare, and the fin material had excellent corrosion resistance and was free of defects.

On the other hand, the fin material of the comparative example has flare jumps caused by the drawless press processing, which causes defects in the fin material.For example, the corrosion resistance as a fin material is satisfactory, and the heat exchange The efficiency was not very good, and furthermore, the formability of drawless press processing was also not good.

In addition, as in the above embodiments, by making the surface film formed on the aluminum surface highly hydrophilic as in the case of embodiment 1, for example, the sub-chlorine of alkali metals or alkaline earth metals can be removed. In the case of an oxide film formed by forming an oxide film with an aqueous solution of an acid salt or a bromate salt, and then treating it with a silicate solution, the oxide film is formed into a fin material by drawless pressing, and then degreased with a trichloride solution. Even though
The water wettability of the surface of the fin material does not deteriorate much, which is extremely desirable.

In addition, the thickness of the oxide film formed on the surface of the wrought material is approximately 2 to 10
tI1g/謔, especially about 5-8Ir! By setting g/dr to 111, not only the drawless press workability is good, but also it is desirable in terms of both heat exchange efficiency and corrosion resistance.

As mentioned above, the method for producing a heat exchange medium according to the present invention is to apply a thick film to aluminum or aluminum alloy material: about 2 to 1O
After forming the surface oxide film of /drrI2, this material t
Since the heat exchange medium is manufactured by drawless press processing, the heat exchange medium can be efficiently manufactured by drawless press processing, and the manufacturing cost is low. Even though it is formed, no defects occur during drawless press processing, and for example, it is possible to create a heat exchange medium with excellent corrosion resistance and heat exchange efficiency, and it also has features such as good drawless press workability. have

Patent applicant Mitsubishi Aluminum Co., Ltd. Representative
People U Gao Tun Self.

Claims (1)

[Claims] Aluminum or aluminum alloy material with a film thickness of approximately 2 to 100 t
omg/an? A method for producing a heat exchange medium, which comprises forming a surface oxide film on the material and then subjecting the material to drawless pressing to produce a heat exchange medium.